StarCraft

Starcraft is still one of the consummate real time strategy games. In fact, it is perhaps the consummate real time strategy game. The RTS genre was pretty well established with Blizzard's Warcraft and Westwood's Dune II, but it didn't change significantly until Starcraft came out in 1998, pioneering the concept of dramatically different races in one game.
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Starcraft offers a lengthy single-player campaign featuring ten missions for its three diverse races, totaling 30 single-player missions in all (there's also an unsupported veteran campaign included as part of the campaign editor). The story is compelling enough to make playing through all three worthwhile, and the campaign difficulty is tiered so that each is more challenging than the last.
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